[PATCH 5.4 34/34] scsi: core: Fix race between handling STS_RESOURCE and completion

Greg Kroah-Hartman
2022-08-01T11:52:13Z

From: Ming Lei <ming.lei@redhat.com>

commit 673235f915318ced5d7ec4b2bfd8cb909e6a4a55 upstream.

When queuing I/O request to LLD, STS_RESOURCE may be returned because:

- Host is in recovery or blocked

- Target queue throttling or target is blocked

- LLD rejection

In these scenarios BLK_STS_DEV_RESOURCE is returned to the block layer to
avoid an unnecessary re-run of the queue. However, all of the requests
queued to this SCSI device may complete immediately after reading
'sdev->device_busy' and BLK_STS_DEV_RESOURCE is returned to block layer. In
that case the current I/O won't get a chance to get queued since it is
invisible at that time for both scsi_run_queue_async() and blk-mq's
RESTART.

Fix the issue by not returning BLK_STS_DEV_RESOURCE in this situation.

Link: https://lore.kernel.org/r/20201202100419.525144-1-ming.lei@redhat.com
Fixes: 86ff7c2a80cd ("blk-mq: introduce BLK_STS_DEV_RESOURCE")
Cc: Hannes Reinecke <hare@suse.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ewan Milne <emilne@redhat.com>
Cc: Long Li <longli@microsoft.com>
Reported-by: John Garry <john.garry@huawei.com>
Tested-by: "chenxiang (M)" <chenxiang66@hisilicon.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/scsi_lib.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1719,8 +1719,7 @@ out_put_budget:
case BLK_STS_OK:
break;
case BLK_STS_RESOURCE:
- if (atomic_read(&sdev->device_busy) ||
- scsi_device_blocked(sdev))
+ if (scsi_device_blocked(sdev))
ret = BLK_STS_DEV_RESOURCE;
break;